Composite pipe



April 19, 1949.

J. F. STEPHENS COMPOS ITE PIPE 2 Sheets-Sheet 1 Filed June 23, 1944 a; ran/5x April 19, 1949.

J. F. STEPHENS COMPOSITE PIPE 2 Sheets-Sheet 2 Filed June 23, 1944 u h F 2 ose e was .BY Z

Ptented Apr. 1 9, 1949 COMPOSITE PIPE Joseph F. Stephens, Kansas City, Mo., assignor to Gustin-Bacon ManufacturingCompany, a corporation of Missouri Application June 23, 1944,'Serial No. 541,814

6 Claims.

This invention relates to improvements in composite pipe and the processes for making the same and refers more particularly to a process of producing the pipe made up of reinforcing fibers bonded together with a plastic binder, which composition forms the peripheral shell of the pipe and is seasoned or cured to a unitary rigid structure.

The salient feature of novelty resides in the manner in which the long fiber reinforcement is layed up or wound circumferentiallyof the pipe in superposed layers after having been immersed or run through a bath of plastic bonding material.

It is conventional practice at present to form composite pipe with a mixture of fiber reinforcement incorporated in a plastic or bonding material, but in the formation of such pipe the fibers are mixed with the binder before the pipe is formed. This process does not permit the use of long fibers because of the difficulty attendant with the mixing of such fibers with the binder. Furthermore, the employment of short fibers limits the strength of the fiber reinforcement and permits but a limited orientation of the fibers in the direction of the working stress of the pipe.

In other words, the short fibers arrange themselves haphazardly throughout the binder, while long fibers of greater strength can, if properly handled, be layed 'up or oriented with respect to the peripheral shell of the pipe so that a maximum advantage may be obtained of their reinforcement characteristics.

Where fibers are spun into threads and the threads woven into cloth and the cloth used as reinforcement, as in the manufacture of flexible hose or tubing, the crimp of the threads caused by weaving the weft over and under the warp in the loom detracts from the effective strength of the thread reinforcement, since a relatively slight tensile stress on the cloth will produce an appreciable elongation due to the straightening of the crimp. The principal purpose of weaving the fiber into cloth before using it as reinforcement is to provide convenience in handling the reinforcement in building up the pipe or tubing. The weaving operation is, therefore, not only an added expense but serves to deteriorate and reduce the reinforcement strength of the fiber. By eliminating crimping of the fibers in the weaving operation and applying the fibers with the plastic or binder in layers to lay the fiber circumferentially about the pipe the maximum strength of the fibers as reinforcement is obtained.

In the accompanying drawings which form a part of the specification and are to be read in 2 spective an apparatus for manufacturing pipe in which a web of straight fiber serves as the reinforcement, and

Fig. 2 is a diagrammatic view showing in perspective an apparatus in which a band of fibers is spirally wound in superposed layers as the reinforcement.

Referring to the drawings and particularly'to Fig. 1, the entering web to be utilized as reinforcement for the pipe section to be formed is shown at I0. This web is made up of a mass of loose fibers by either a dry process, such as a carding or garnet machine common in the textile industry, or by a wet process, such as is used in the paper industry. The web is formed of fibers oriented generally in a longitudinal direction although the fibers may, to an extent at least, be felted or matted together giving the mat suflicient strength to be self supporting. The character of the fibers used, while of importance to the strength of the pipe section produced, is of minor importance to the inventive concept. The description of the steps of the process for producing composite pipe, according to the invention, contemplates the use of fiber glass as reinforcement fiber but the selection of this type of fiber is not to be considered as limiting the invention to such fiber. Likewise, the plastic or binder employed may be varied according to the purpose for which the pipe is to be used and the strength needed. Cement mixtures, bituminous substances or organic plastics all are contemplated as well as other binders adapted for the manufacture of pipes, conduits or tubing. Asbestos fiber may be used in place of fiber glass as reinforcement. Vegetable fiber, hair or other organic materials and inorganic fibers may be used instead of fiber glass or asbestos as well as mixtures of any of these fibers.

The feature of novelty, as previously suggested, lies not in the characteristics of the reinforcement fibers nor the character of the binder but in the use of long fibers of greater strength which can be layed up circumferentially in superposed layers after immersion in the binder and seasoning or curing of the bonded mass of fibrous layers and binder after forming.

Returning to the manufacture of pipe in the apparatus shown in Fig. 1, the entering web is fed over a roll I I and beneath two immersion rolls I2 and I3 where an application of binder is given to the fibers of the web; The binder substance is contained in a reservoir or tank I 4 above which the rolls I2 and I3 are'positioned. After receiving an application of the binder the web is rolled onto the peripheral surface of a mandrel l5 where the superposed layers are bonded together in a unitary mass by compression rolls l6. When the layers of the web have been rolled onto the mandrel in suificient thickness the web is severed by cutter blades I1 and the pipe permitted to harden on the mandrel or removed therefrom and seasoned or cured separately. The apparatus for forming the pipe including the mandrel, compression rolls and mechanism for applying the binder to the web have all been shown in diagrammatic form in the interest of simplicity since they employ apparatus conventional in the production of composite pipe or tubing.

The pressure between the compression rolls and the mandrel or the pressure applied to the surface of the rotating mandrel during the building up operation or application of the successive layers is regulated to produce the desired texture and consistency in the peripheral shell of the formed tube. Hydraulic, spring or weight operated mechanism may be used to impose this pressure. The purpose of the compression rolls is to produce the-desired denseness to the structure of the pipe shell.

Furthermore, it is contemplated that other variations in the process may be employed without departing from the inventions scope. The web, under certain conditions and when using certain types of fiber, may not have sufficient strength to be brought over and under the rolls without support. In such case the web may be carried upon a belt up to the point where it is wound onto the mandrel surface. The binder may be applied by other methods than by immersion -or dipping the web. It may be sprayed onto the web or applied to the web after application of the web to the mandrel by a pick-up roll or belt. Some method of partial or complete drying may be required between the points where the binder is applied to the web and the mandrel. It may be found advisable and necessary to heat or cool the mandrel or compression rolls to assist or facilitate the compacting of the materials after application to the mandrel to prevent adhesion to the compression rolls. After the pipe is built up to the desired thickness, it may be cured either on or off the mandrel by subjecting it to heat or moisture. The web may be built up directly on the mandrel, or an inner tube or liner may first be placed on the mandrel and the web applied to this liner in the event the finished pipe is to be made more impervious or protected from the action of fluids carried by the pipe.

In other words, the type of materials used both for the binder and reinforcement fibers, and the methods employed in making the pipe will all be dependent upon the characteristics desired and necessary to the final product.

The apparatus depicted and the process employed in Fig. 2 is similar to that shown in Fig. except that a band of fiber is used as reinforcement instead of a wide web. Also the band is wound helically or in a plurality of spiral courses or superposed layers upon the mandrel instead of by straight application as is the web in Fig. 1. The band 18 made up of a plurality of long fibers after being preliminarily formed by conventional methods is fed over roll H and beneath the immersion roll l2 where an application of binder is made to the band in the reservoir or tank I. The flanged spool l9 reciprocated lengthwise of the shaft 20 by shuttle mechanism not shown feeds the band of fibers onto mandrel IS in superposed layers spirally wound as shown in Fig. 2 of the drawing. Compression rolls l6 impose predetermined pressure upon the layers of reinforcement and bonding substances during the pipe forming operation to produce a dense unitary structure to its peripheral shell. When the shell of the pipe has been built up to the desired thickness cutters I'I sever the band and the pipe is removed from the mandrel by conventional methods before or after proper seasoning and curing. The process steps as well as the character of the binder and fibers may be varied at will according to the final product desired. Instead of a ribbon of continuous untwisted parallel fibers a ribbon of threads or cord may be used. The threads may be made up of twisted continuous or discontinuous fibers and the cord may be made up of several twisted threads. Methods for applying the binder may be varied as described in the process of Fig. 1. Other variables suggested in connection with the process of Fig. 1 are applicable as well to the method of Fig. 2. In this figure, as in the previous figure,

details of the apparatus have been reduced to a minimum in the interest of simplicity.

From the foregoing it will be seen that the invention is well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and inherent to the process or product obtained therefrom. As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. Fiber reinforced composite pipe consisting of long reinforcing fibers layed up circumferentially in superposed layers to form the peripheral shell of the pipe, said fibers bonded'with a cured plastic.

2. Fiber reinforced composite pipe consisting of reinforcing fibers helically wound in superposed layers to form the peripheral shell of the pipe, said fiber layers bonded with a cured plastic material.

3. A composite pipe as in claim 1 in which the reinforcement comprises mineral fibers of the class of glass fiber and asbestos fiber.

4. A composite pipe as in claim 1 in which the reinforcement comprises organic fibers of the class of hair and vegetable fibers.

5. A composite pipe as in claim 2 in which the reinforcement comprises mineral fibers of the class of glass fiber and asbestos fiber.

6. A composite pipe as in claim 2 in which the reinforcement comprises organic fibers of the class of hair and vegetable fibers.

JOSEPH F. STEPHENS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 444,233 Denney Jan. 6, 1891 603,230 Bergmann Apr. 26, 1898 684,604 Dixon Oct. 15, 1901 1,166,432 Case Jan. 4, 1916 1,284,295 Frederick Nov. 12, 1918 1,316,591 Perry Sept. 23, 1919 1,344,321 Urbina June 22, 1920 1,396,021 Burningham Nov. 8, 1921 2,010,475 Bowen Aug. 6, 1935 2,256,386 Farrar et al. Sept. 16, 1941 

